Perilla

The classification of Perilla is confused, partly because botanists struggled with distinguishing the two distinct cultigens as different species or variations.[1][5] Until a few decades ago, P. frutescens var. crispa was regarded as a species in its own right, distinct from P. frutescens, although it was well established that these types readily cross-pollinate.[6] An early example of dividing the two cultigens into different species is found in Matsumura's 1884 nomenclature book, where the synonym P. arguta Benth. is applied to P. frutescens var. crispa, and the synonym P. ocymoides L. was applied to P. frutescens.[7][8][9][10] The species name P. ocymoides or P. ocimoides has historically been used to denote P. frutescens var. crispa, especially by the Japanese,[lower-alpha 1][6] therefore it should not be considered an interchangeable synonym for either cultigen. Recent genetic research confirms that the cultigens are of a common gene pool, corroborating the taxonomists' claim for consolidating the two crops into one species.[11]

Existing Perilla species:

• P. frutescens – also called Korean perilla or deulkkae; the leaves are called kkaennip
  • P. f. var. crispa – also called shiso, tía tô, or Japanese basil[12]
  • P. f. var. hirtella – also called lemon perilla[13]

Possible Perilla species with insufficient description and without known herbarium specimens include:

• P. cavaleriei H.Lév.
• P. heteromorpha Carrière
• P. setoyensis G.Honda

The past legacies and subsequent reclassification of taxa has led to confusion of nomenclature.[14][5] The red or purple leafed variety of P. frutescens var. crispa had been dubbed P. nankinensis,[5] and this label was used throughout the 19th century in the West following the introduction of the species for ornamental planting. Whether green-leafed or red-leafed, the perillaldehyde factor that characterizes the unique P. frutescens var. crispa fragrance may turn out to be present or absent in the individual or population, and this is not differentiable from outward appearance alone. Chemical studies classify the genus into different chemotypes, depending on the essential oils they contain. Three wild species that are endemic to Japan are recognized as genetically distinct from the cultivated P. frutescens var. crispa,[11] however, some references treat, e.g., P. frutescens var. hirtella as the same species as the P. frutescens var. crispa.[10]

Formerly placed here

Kkaennip, the edible leaves of Perilla frutescens (P. frutescens)

Aojiso, the edible leaves of Perilla frutescens var. crispa (P. frutescens var. crispa)

• P. elata D.Don. = Elsholtzia blanda (Benth.) Benth.[15]
• P. fruticosa D.Don = Elsholtzia fruticosa (D. Don) Rehder[15][16]
• P. lanceolata Benth = Mosla scabra (Thunb.) C.Y.Wu & H.W.Li
• P. leptostachya D.Don. = Elsholtzia stachyodes (Link) Raizada & H.O.Saxena[15][17]
• P. marathrosma Spreng. = Agastache foeniculum (Pursh) Kuntze
• P. nankinensis Wender. = Plectranthus scutellarioides (L.) R.Br.
• P. polystachya D.Don. = Elsholtzia ciliata (Thunb.) Hyl.[15]